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Help FZR 250 R 3LN1 Spark plug type

Discussion in 'Yamaha 250cc In-Line 4's' started by Bobbyr, Jan 18, 2021.

  1. Bobbyr

    Bobbyr Member

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    Hi can anyone advise me into the correct type of replacement spark plugs I need for my bike? many thanks
     
  2. ajb0235

    ajb0235 Active Member

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    Just taken the plugs out of my 3LN 1989 model.
    Plugs are NGK CR9EK.
    I don't know what the original fitment is, but these seemed to run OK in the short time I have had the bike.
     
  3. Bobbyr

    Bobbyr Member

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    Oh brilliant thanks, I think that they are the same as mine but again wasn’t sure if these are the OEM plugs.
    Thank you for that
     
  4. Linkin

    Linkin The Mechanic Premium Member Contributing Member Dirty Wheel Club

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    Standard plugs should be CR8E
     
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  5. driftwood

    driftwood Well-Known Member

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    I tried the Champion G59C and was happy for awhile, but then it too fouled and couldn't be cleaned. Ordered some Bosch UR2CC, wait and see see.
     
  6. Cj Ryder

    Cj Ryder Member

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    Standard for what rating tho? Do CPR6ea-9 give the same feed almost?


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  7. Linkin

    Linkin The Mechanic Premium Member Contributing Member Dirty Wheel Club

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    The letters and numbers on the plugs are important.

    https://www.ngk.com/ngk-spark-plug-numbering-systems

    Depending on the type of ignition system on the motorcycle, certain types of plugs are needed.

    In this case, CR8E means the following

    C = 10mm thread

    R = Resistor

    8 = Heat range (2 being the hottest on the scale, 12 being the coldest on the scale)

    E = 19mm Reach, or length of the threaded section.


    Compare that to the CPR6EA-9

    C = 10mm thread

    P = Projected insulator

    R = Resistor

    6 = Heat range 6

    E = 19mm Reach

    A = Special Design (not sure on specifics)

    9 = 0.9mm Gap from tip to electrode


    You should use either the standard plug or a variant of it. For example, a CR8EK plug is just a CR8E with two prongs on the end, theoretically they last twice as long. A CR8EIX is an Iridium version of the CR8E.

    The physical dimensions of a plug are important, you don't want the plug to protrude too far into the cylinder and make contact with the piston or the valves. Too short and it will reduce compression and not give a clean burn. Resistor/non resistor type means using the wrong type will result in no spark at best, a blown fuse if you are lucky, or destroyed ignition system in the worst case scenario.
     
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  8. Cj Ryder

    Cj Ryder Member

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    Dude thanks that made sense the cylinder 2&3 the sparks felt kinda out of place when I looked at them like 1 & 4 where in place and leveled yet again 2&3 where not in too deep apparently can't post pictures till the end of the month


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  9. Cj Ryder

    Cj Ryder Member

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    I’m going to attempt a crank with the 6 I know it sux with the heat range going sorta off to hot but with my options it’s either that or the copy plugs that well god know what’ll happen so the cpr6ea 9’s still inside if it runs I’ll definitely have to find sparks somewhere btw finding the right sparks always gets me I end up getting-either short threads or low heat whenever I go to get sparks they ask about the size of the thread and numbers well maybe they dunno the charts of what they’re selling they just care it’ll fit so 6heat range for now ouch stil hope it’ll run tho


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  10. Tonino

    Tonino Active Member

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    Is it correct that With NGK resistor caps resistor plugs should not be used as the spark is greatly reduced? If so what is the non resistor equivalent?
     
    Last edited by a moderator: Oct 26, 2021
  11. Linkin

    Linkin The Mechanic Premium Member Contributing Member Dirty Wheel Club

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    Use what the bike manufacturer states. On the 3LN the plug cap is a resistor type, 10k ohm if I remember correctly. The resistors are there to prevent electromagnetic interferrence, either from the ignition system or to prevent other interference affecting ignition
     
  12. Murdo

    Murdo The Good Doctor Staff Member Contributing Member Ride and Events Crew

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    Just take the R from the plug numbers eg, BPR9es is resistor type, BP9es is non-resistor.
     
  13. risky

    risky risky

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    try cr8eix and i am sure you will be happy.
     

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